SNP Westminster leader Angus Robertson is "open" to the party dropping its support for a currency union with the rest of the UK after independence and instead creating a Scottish pound.

The Moray MP made the comment in a depute leader debate with the other candidates on Scotland Tonight.

Robertson, who led the SNP's campaign for independence in 2014, is considered to be the front runner in the contest.

He told STV: "You ask me for my preference to the currency.

"I am open to the prospect of a Scottish pound. We cannot rule out other options and that's why we have to go through a process which involves internal debate, internal discussion and an agreement across the party."

His three rival candidates Tommy Sheppard MP, Alyn Smith MEP and Councillor Chris McEleny also said they would consider a change in the party's current policy.

Their comments were made on the same day an economic adviser to Nicola Sturgeon said the party's currency policy "may have been a mistake".

Smith said the downside to the SNP's support for a formal currency union with the rest of the UK in 2014 was that it relied upon the "goodwill of our opponents".

During the referendum the then Chancellor George Osborne ruled out allowing an independent Scotland to formally use the pound.

The MEP said the policy was a "weakness" and "didn't quite work" due to the reliance on the UK Government.

He refused to rule out adopting the Euro.

Edinburgh East MP Tommy Sheppard said the party "do not make policy on late night TV programmes" but following the events of the EU referendum in June a Sterling union has been thrown "somewhat of a big question mark".

Sheppard said he was open to all possible currency arrangements.

Inverclyde councillor Chris McEleny backed an independent Scottish currency during the depute leader debate.

He said: "We have an economy that over 100 independent countries in the world would envy.

"If we support that economy and if we think it is strong enough to make us an independent country then, I am no economist, but I think that means we can support our own currency".

The First Minister was questioned on her party's stance on a currency union in London at an EU referendum hustings event in June.

The First Minister said the pound is "our currency" and she believes Scotland "should continue to use" it after independence.

Sturgeon will launch an independence initiative in Stirling on Friday at a meeting of the party's MPs and MSPs.